1. Field of the Invention
The present invention relates to a laser display device and an optical coupler therefor, and more particularly, to a laser display device, which eliminates speckles generated in the transmission of laser beams and uniformly mixes laser beams of various colors, and an optical coupler therefor.
2. Discussion of the Related Art
Recently, display devices using various light sources have been manufactured. Among various light sources, a laser light source has a wide color temperature, and is advantageous in that a displayed image are expressed in colors, which are close to natural colors, thus trying to be applied to a display field.
However, when the laser light source is used in display devices, speckles occur due to the coherence of laser beams in that the laser beams have the same special and temporal phases.
When light having coherence, such as a laser beam, is reflected by the surface of an object, the light is dispersed due to the roughness of the surface. In case that a detector has a limited aperture (for example, a human eye) sees the light, speckles are detected by the detector.
That is, speckles differ from spots, which occur due to a variation of image or beam intensity distribution by defects of an optical system passing laser beams.
Accordingly, in order to manufacture a high definition display device having excellent color reproduction and color purity, speckle noise must be reduced.